In order to increase the useful longevity of cells and batteries both for military and civilian use, it is desired that such electrochemical energy sources be kept at a ready condition until the energy is required. In this manner the operating cycle of the device is only initiated at the time the operation of the device is required. Such devices have been described as "reserve" cells in that the energy output is withheld or reserved until required. Moreover in such devices it is required that the operation of the device be positive and foolproof. Further, recently it has become desirable to provide cells and batteries with high voltage electrochemical couples. The advantages therein lie in that the voltage from each cell couple is in the order of 2 volts to 3.5 volts. Such high energy electrochemical couples are based primarily on the use of highly active anodic metals. These active metals are those which lie above hydrogen in the electrochemical series i.e., they are capable of displacing hydrogen from water. Because of this capability of displacing hydrogen from water, water-based electrolytes cannot be safely used therewith. When water is used in conjunction with high energy electrochemical couples and particularly such couples involving anodic materials such as lithium, sodium, potassium and calcium, contact of the electrolyte with the anodic material will liberate copious amounts of hydrogen and oxygen which upon accumulation within the cell chamber may form explosive mixtures. For this reason it is preferred to use organic electrolytes in conjunction with such materials. Consequently the electrolyte should be based upon organic solvents.
Many of the organic electrolyte cells consist of: (a) active, high-voltage, light metal anodes such as lithium, (b) a wide variety of depolarizers including metal halides, oxides, perioxides, chromates, permanganates, periodates, molybdates, vanadates, arsenates, phosphates, sulfates, etc. and (c) a wide variety of electrolytes consisting of organic solvents such as tetrahydrofuran, propylene carbonate, gamma-butyrolactone, dimethylsulfite, N-nitrosodimethylamine, methylformate, dimethylcarbonate, N:N dimethylformamide, butylformate, acetonitrile, dimethoxyethane, dimethylsulfoxide etc. with a wide variety of dissolved active metal salts such as perchlorates, tetrachloroaluminates, tetrafluoroborates, chlorides, hexafluorophosphates, hexafluoroarsenates, etc. of the active metals. Such cells, when the electrodes are maintained immersed in the electrolytes even though the electrochemical circuit is not completed, show a degradation of performance on prolonged storage at elevated temperatures. This problem is due to spontaneous chemical reaction between the electrolyte and the extremely active anode and cathode materials. This problem is usually eliminated by using a reserve cell structure for these cells wherein the electrolyte is stored in a separate compartment away from the active electrodes and when needed the cell is activated by releasing the electrolyte into the electrode chamber by suitable means.